Vacuum Brazing of SiCp/Al Composites and TC4 Titanium Alloy: Microstructure Evolution and Mechanical Properties

In this paper, a dissimilar material consisting of 55% SiCp/ZL102 composites and TC4 titanium alloy was brazed using Al-8.0 Mg-17.0Cu-1.0Ti foil-like brazing alloy manufactured by rapid solidification technology. Brazing was completed in a vacuum of 1.0 x 10-4 Pa. Si element from Al composites accumulated at the interface of TC4 titanium alloy to form Ti7Al5Si12 intermetallic compound layer. The intermetallic compound alpha 2(TiAl3) grew perpendicular to the brazing seam below 590 degrees C. The alpha 2(TiAl3) intermetallic compound grown into long strips at 590 degrees C. The strip structure had a bonding interface in the form of pinning at a certain angle. The brazing interface was continuous and dense, without defects and exhibited good bonding performance. The shear strength of the brazed joint reached 98.01 MPa at 590 degrees C for 30 min, and the gas tightness was 1.0 x 10-10 Pa m3/s. The brazed joint failed in filler metal due to ductile-brittle mixed fracture mechanism, which resulted in shear lips, parabolic dimples, and furrows in the fracture surface.